This application is related to DE 197 27 655.5 filed on Jun. 30, 1997, which is incorporated by reference in its entirety for all purposes.
The invention relates to a coupling for connecting vacuum-insulated line ends via a coupling socket and a coupling plug which are provided for conveying a cryogenic medium and which have means at the outer line ends that close the line ends.
Couplings for cryogenic media are already known which can be divided into two groups on the basis of their connection mechanism and their means for opening and closing the line ends.
DE 19516029 C1, DE 4041337 A1 and DE 4339676 A1 disclose couplings for cryogenic media which have a coupling plug and a coupling socket. The coupling plug is inserted into the coupling socket so that the outer vacuum-insulated outer coupling housings overlap and a connection element arranged on the outside of the coupling housing can be engaged with a counterpart arranged on the coupling plug. The connection is established by screwing the coupling plug to the coupling socket. During the performed process of sliding the coupling plug into the coupling socket, the coupling is first sealed off against the ambient medium; then the means that close the line ends are opened. The valve-like means in this embodiment of the coupling are located far away from the separation plane inside the coupling socket in the coupling plane.
In the separation plane, the outer faces of the coupling plug and the coupling socket are directly across from each other.
In the coupling plane, the means that close the line ends are directly across from each other. The means can be opened or closed and, when the means are opened, cryogenic medium can flow from the line end of the coupling plug to the line end of the coupling socket.
Moreover, DE 4104711 A1 and U.S. Pat. No. 4,335,747 A1 disclose the technique of sealing against ambient medium separately from the opening/closing of the means directly adjacent to the separation plane by means of ball valves. The connection of the coupling plug with the coupling socket is established with mechanical elements in the separation plane. Likewise far away from the separation plane, in the coupling socket, these couplings have valve-like means whose opening is effectuated by means of the line end of the coupling plug that can be mechanically slid beyond the separation plane and through the opened ball valves all the way to the coupling plane. For this purpose, the line end of the coupling plug is configured to be flexible like a corrugated hose.
From a mechanical and safety-related standpoint, the interlocking screwed connections of the known couplings for opening the valve-like means are not a feasible solution since, for example, a great deal of mechanical and electrical effort is needed with the automatic rotation of the union nut proposed in DE 40 41 337 A1 and this leads to a set-up that can no longer be handled by non-technical personnel in terms of the size and the weight of the coupling. In contrast, the solution proposed in DE 41 04 711 A1, namely, to slide the line end by turning a setscrew until the valve-like means opens, leads to a complicated mechanical construction of the means and of the line end ensuring the seal between the coupling plug and the coupling socket. However, the instructions disclosed in DE 195 16 029 C1, i.e., to exert the force by means of a lever, a cam or a cylinder powered by an outside medium during the plugging and connecting of the coupling plug with the coupling socket, only follows the path indicated by the known state of the art described above, namely, to connect the coupling housings to each other by means of a relative movement. Here, the valve-like means are located far away from the separation plane inside the coupling socket. The plug-in/push-in connection is unsatisfactory from a safety standpoint when the coupling socket is located as a refueling device (tank closure) on a vehicle and the coupling plug is located on a pump of a service station, since the plug-in connection can cause serious damage to the service station and/or the vehicle if the vehicle drives away while it is still connected, even if the coupling plug is separated form the coupling socket in the separation plane and the coupling plug to the coupling socket is located in the coupling plane. In addition, during the refueling of cryofuel tanks of vehicles, lay persons operate the coupling, which calls for a simple and safe design of the coupling so that the users do not come into contact with the cryogenic fuel.
Therefore, couplings for cryogenic media would be desirable in which the disadvantages according to the state of the art are avoided.